gh-84393: Remove AIX workaround: re-enable posix_fadvise and f_allocate (GH-144784)

Co-authored-by: Batuhan Taskaya <batuhanosmantaskaya@gmail.com>

Author: encukou

Misc/NEWS.d/next/Library/2020-04-07-05-09-34.bpo-40212.oPYeBs.rst

@@ -0,0 +1 @@
+Re-enable :func:`os.posix_fallocate` and :func:`os.posix_fadvise` on AIX.

Modules/clinic/posixmodule.c.h

@@ -13376,19 +13376,9 @@ os_truncate_impl(PyObject *module, path_t *path, Py_off_t length)
 #endif /* HAVE_TRUNCATE || MS_WINDOWS */
 
 
-/* Issue #22396: On 32-bit AIX platform, the prototypes of os.posix_fadvise()
-   and os.posix_fallocate() in system headers are wrong if _LARGE_FILES is
-   defined, which is the case in Python on AIX. AIX bug report:
-   http://www-01.ibm.com/support/docview.wss?uid=isg1IV56170 */
-#if defined(_AIX) && defined(_LARGE_FILES) && !defined(__64BIT__)
-#  define POSIX_FADVISE_AIX_BUG
-#endif
-
-
 /* GH-111804: Due to posix_fallocate() not having consistent semantics across
    OSs, support was dropped in WASI preview2. */
-#if defined(HAVE_POSIX_FALLOCATE) && !defined(POSIX_FADVISE_AIX_BUG) && \
-    !defined(__wasi__)
+#if defined(HAVE_POSIX_FALLOCATE) && !defined(__wasi__)
 /*[clinic input]
 os.posix_fallocate
 
@@ -13426,10 +13416,10 @@ os_posix_fallocate_impl(PyObject *module, int fd, Py_off_t offset,
     errno = result;
     return posix_error();
 }
-#endif /* HAVE_POSIX_FALLOCATE) && !POSIX_FADVISE_AIX_BUG && !defined(__wasi__) */
+#endif /* HAVE_POSIX_FALLOCATE && !defined(__wasi__) */
 
 
-#if defined(HAVE_POSIX_FADVISE) && !defined(POSIX_FADVISE_AIX_BUG)
+#if defined(HAVE_POSIX_FADVISE)
 /*[clinic input]
 os.posix_fadvise
 
@@ -13473,7 +13463,7 @@ os_posix_fadvise_impl(PyObject *module, int fd, Py_off_t offset,
     errno = result;
     return posix_error();
 }
-#endif /* HAVE_POSIX_FADVISE && !POSIX_FADVISE_AIX_BUG */
+#endif /* HAVE_POSIX_FADVISE */
 
 
 #ifdef MS_WINDOWS